NetXMS Support Forum

According to the documentation, ReadPersistentStorage() is suppose to return null if key does not exist but it seems to be returning an empty string ("") for a recently deleted (This is all happening within EPP) Persistent Storage value.

Is this a bug?

So you are deleting also from EPP?
If you are deleting from NXSL, do you delete like this:
WritePersistentStorage("key1", NULL);

It's a known bug - https://track.radensolutions.com/issue/NX-1897. Fixed in 3.4.284.

Best regards,
Victor